1 files changed, 151 insertions, 0 deletions
diff --git a/scripts/gen_compile_commands.py b/scripts/gen_compile_commands.py
new file mode 100755
index 000000000000..7915823b92a5
--- /dev/null
+++ b/scripts/gen_compile_commands.py
@@ -0,0 +1,151 @@
+#!/usr/bin/env python
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) Google LLC, 2018
+#
+# Author: Tom Roeder <tmroeder@google.com>
+#
+"""A tool for generating compile_commands.json in the Linux kernel."""
+
+import argparse
+import json
+import logging
+import os
+import re
+
+_DEFAULT_OUTPUT = 'compile_commands.json'
+_DEFAULT_LOG_LEVEL = 'WARNING'
+
+_FILENAME_PATTERN = r'^\..*\.cmd$'
+_LINE_PATTERN = r'^cmd_[^ ]*\.o := (.* )([^ ]*\.c)$'
+_VALID_LOG_LEVELS = ['DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL']
+
+# A kernel build generally has over 2000 entries in its compile_commands.json
+# database. If this code finds 500 or fewer, then warn the user that they might
+# not have all the .cmd files, and they might need to compile the kernel.
+_LOW_COUNT_THRESHOLD = 500
+
+
+def parse_arguments():
+    """Sets up and parses command-line arguments.
+
+    Returns:
+        log_level: A logging level to filter log output.
+        directory: The directory to search for .cmd files.
+        output: Where to write the compile-commands JSON file.
+    """
+    usage = 'Creates a compile_commands.json database from kernel .cmd files'
+    parser = argparse.ArgumentParser(description=usage)
+
+    directory_help = ('Path to the kernel source directory to search '
+                      '(defaults to the working directory)')
+    parser.add_argument('-d', '--directory', type=str, help=directory_help)
+
+    output_help = ('The location to write compile_commands.json (defaults to '
+                   'compile_commands.json in the search directory)')
+    parser.add_argument('-o', '--output', type=str, help=output_help)
+
+    log_level_help = ('The level of log messages to produce (one of ' +
+                      ', '.join(_VALID_LOG_LEVELS) + '; defaults to ' +
+                      _DEFAULT_LOG_LEVEL + ')')
+    parser.add_argument(
+        '--log_level', type=str, default=_DEFAULT_LOG_LEVEL,
+        help=log_level_help)
+
+    args = parser.parse_args()
+
+    log_level = args.log_level
+    if log_level not in _VALID_LOG_LEVELS:
+        raise ValueError('%s is not a valid log level' % log_level)
+
+    directory = args.directory or os.getcwd()
+    output = args.output or os.path.join(directory, _DEFAULT_OUTPUT)
+    directory = os.path.abspath(directory)
+
+    return log_level, directory, output
+
+
+def process_line(root_directory, file_directory, command_prefix, relative_path):
+    """Extracts information from a .cmd line and creates an entry from it.
+
+    Args:
+        root_directory: The directory that was searched for .cmd files. Usually
+            used directly in the "directory" entry in compile_commands.json.
+        file_directory: The path to the directory the .cmd file was found in.
+        command_prefix: The extracted command line, up to the last element.
+        relative_path: The .c file from the end of the extracted command.
+            Usually relative to root_directory, but sometimes relative to
+            file_directory and sometimes neither.
+
+    Returns:
+        An entry to append to compile_commands.
+
+    Raises:
+        ValueError: Could not find the extracted file based on relative_path and
+            root_directory or file_directory.
+    """
+    # The .cmd files are intended to be included directly by Make, so they
+    # escape the pound sign '#', either as '\#' or '$(pound)' (depending on the
+    # kernel version). The compile_commands.json file is not interepreted
+    # by Make, so this code replaces the escaped version with '#'.
+    prefix = command_prefix.replace('\#', '#').replace('$(pound)', '#')
+
+    cur_dir = root_directory
+    expected_path = os.path.join(cur_dir, relative_path)
+    if not os.path.exists(expected_path):
+        # Try using file_directory instead. Some of the tools have a different
+        # style of .cmd file than the kernel.
+        cur_dir = file_directory
+        expected_path = os.path.join(cur_dir, relative_path)
+        if not os.path.exists(expected_path):
+            raise ValueError('File %s not in %s or %s' %
+                             (relative_path, root_directory, file_directory))
+    return {
+        'directory': cur_dir,
+        'file': relative_path,
+        'command': prefix + relative_path,
+    }
+
+
+def main():
+    """Walks through the directory and finds and parses .cmd files."""
+    log_level, directory, output = parse_arguments()
+
+    level = getattr(logging, log_level)
+    logging.basicConfig(format='%(levelname)s: %(message)s', level=level)
+
+    filename_matcher = re.compile(_FILENAME_PATTERN)
+    line_matcher = re.compile(_LINE_PATTERN)
+
+    compile_commands = []
+    for dirpath, _, filenames in os.walk(directory):
+        for filename in filenames:
+            if not filename_matcher.match(filename):
+                continue
+            filepath = os.path.join(dirpath, filename)
+
+            with open(filepath, 'rt') as f:
+                for line in f:
+                    result = line_matcher.match(line)
+                    if not result:
+                        continue
+
+                    try:
+                        entry = process_line(directory, dirpath,
+                                             result.group(1), result.group(2))
+                        compile_commands.append(entry)
+                    except ValueError as err:
+                        logging.info('Could not add line from %s: %s',
+                                     filepath, err)
+
+    with open(output, 'wt') as f:
+        json.dump(compile_commands, f, indent=2, sort_keys=True)
+
+    count = len(compile_commands)
+    if count < _LOW_COUNT_THRESHOLD:
+        logging.warning(
+            'Found %s entries. Have you compiled the kernel?', count)
+
+
+if __name__ == '__main__':
+    main()